net: refine {udp|tcp|sctp}_mem limits
Current tcp/udp/sctp global memory limits are not taking into account
hugepages allocations, and allow 50% of ram to be used by buffers of a
single protocol [ not counting space used by sockets / inodes ...]
Lets use nr_free_buffer_pages() and allow a default of 1/8 of kernel ram
per protocol, and a minimum of 128 pages.
Heavy duty machines sysadmins probably need to tweak limits anyway.
References: https://bugzilla.stlinux.com/show_bug.cgi?id=38032
Reported-by: starlight <starlight@binnacle.cx>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 48cd88e..198f75b 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -2209,16 +2209,10 @@
void __init udp_init(void)
{
- unsigned long nr_pages, limit;
+ unsigned long limit;
udp_table_init(&udp_table, "UDP");
- /* Set the pressure threshold up by the same strategy of TCP. It is a
- * fraction of global memory that is up to 1/2 at 256 MB, decreasing
- * toward zero with the amount of memory, with a floor of 128 pages.
- */
- nr_pages = totalram_pages - totalhigh_pages;
- limit = min(nr_pages, 1UL<<(28-PAGE_SHIFT)) >> (20-PAGE_SHIFT);
- limit = (limit * (nr_pages >> (20-PAGE_SHIFT))) >> (PAGE_SHIFT-11);
+ limit = nr_free_buffer_pages() / 8;
limit = max(limit, 128UL);
sysctl_udp_mem[0] = limit / 4 * 3;
sysctl_udp_mem[1] = limit;